Automated holographic-based tunnel-type laser scanning system for omni-directional scanning of bar code symbols on package surfaces facing any direction or orientation within a three-dimensional scanning volume disposed above a conveyor belt

ABSTRACT

A fully automated package identification and measuring system, in which an omni-directional laser scanning system are used to read bar codes on packages entering the tunnel, while a package dimensioning subsystem is used to capture information about the package prior to entry into the tunnel. Mathematical models are created on a real-time basis for the geometry of the package and the position of the laser scanning beam used to read the bar code symbol thereon. The mathematical models are analyzed to determine if collected and queued package identification data is spatially and/or temporally correlated with package measurement data using vector-based ray-tracing methods, homogeneous transformations, and object-oriented decision logic so as to enable simultaneous tracking of multiple packages being transported through the scanning tunnel.

CROSS-REFERENCE TO RELATED CASES

This is a Continuation-in-Part of application Ser. Nos.: 08/949,915filed Oct. 14, 1997; 08/854,832 filed May 12, 1997 now 6,089,978;08/886,806 filed Apr. 22, 1997 now 5,984,185; 08/726,522 filed Oct. 7,1996 now 6,073,846; and 08/573,949 filed Dec. 18, 1995 now abandoned,each said application being commonly owned by Assignee, MetrologicInstruments, Inc., of Blackwood, New Jersey, and incorporated herein byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to tunnel type laser scanningsystems arranged about a high-speed conveyor system used in diversepackage routing and transport applications, and also a method ofscanning bar code symbols on surfaces facing any direction with a 3-Dscanning volume disposed above the conveyor system.

2. Brief Description of the Prior Art

In many environments, there is a great need to automatically identifyobjects (e.g. packages, parcels, products, luggage, etc.) as they aretransported along a conveyor structure. While over-the-head laserscanning systems are effective in scanning upwardly-facing bar codes onconveyed objects, there are many applications where it is not practicalor otherwise feasible to ensure that bar code labels are upwardly-facingduring transported under the scanning station.

Various types of “tunnel” scanning systems have been proposed so thatbar codes can be scanned independent of their orientation withinscanning volume of the system. One such prior art tunnel scanning systemis disclosed in U.S. Pat. No. 5,019,714 to Knowles. In this prior artscanning system, a plurality of single scanline scanners are orientatedabout a conveyor structure in order to provide limited degree ofomni-directional scanning within the “tunnel-like” scanning environment.Notably, however, prior art tunnel scanning systems, including thesystem disclosed in U.S. Pat. No. 5,019,714, are incapable of scanningbar code systems in a true omni-directional sense, i.e. independent ofthe direction that the bar code faces as it is transported along theconveyor structure. At best, prior art scanning systems provideomni-directional scanning in the plane of the conveyor belt or inportions of planes orthogonal thereto. However, true omnidirectionalscanning along the principal planes of a large 3-D scanning volume hasnot been hitherto possible.

Thus, there is a great need in the art for an improved tunnel-type laserscanning system and a method of scanning bar code symbols on packagesbeing transported along a high-speed conveyor system, while avoiding theshortcomings and drawbacks of prior art scanning systems andmethodologies.

OBJECTS AND SUMMARY OF THE PRESENT INVENTION

Accordingly, a primary object of the present invention is to provide anovel omni-directional tunnel-type laser scanning system that is free ofthe shortcomings and drawbacks of prior art tunnel-type laser scanningsystems and methodologies.

Another object of the present invention is to provide such a tunnel-typelaser scanning system, wherein bar code symbols that have been placed onany surface of any package, including USPS trays and tubs, and othercustomer mailed products, including the bottom surface of the product,are automatically scanned during movement through the system.

Another object of the present invention is to provide such a tunnel-typescanning system which can be used for high speed mail and parcel sortingsystems (e.g. Large Package Sorting Systems (LPSS), Singulate and ScanInduction Units (SSIU), as well as luggage checking and tracking systemsused in airport terminals, bus-stations, train stations, and the like.

Another object of the present invention is to provide such tunnel-typescanning system, which can read different bar code symbologies (e.g.Interleaved two of five, Code 128 and Code three of nine), code lengths,and formats in accordance with AIM and ANSI Standards.

Another object of the present invention is to provide such a tunnel-typescanning system, in which a user-interface is provided for programmingthe bar code symbologies, code lengths and code formats handled by eachlaser scanning unit within the system.

Another object of the present invention is to provide such a tunnel-typescanning system, for reading bar code symbols on packages having varioustypes of symbol formats, such as ZIP Code symbols (six digits), PackageIdentification Code (PIC) symbols (sixteen characters), and Tray barcode symbols (ten digits).

Another object of the present invention is to provide such a tunnel-typescanning system, for omni-directional scanning of bar code symbols onpackages, parcels and products transported along a high-speed conveyorsystem at velocities in the range of about 100 to 520 feet per minute orgreater.

Another object of the present invention is to provide such a tunnel-typescanning system, in which a plurality of holographic laser scanningsubsystems are mounted from a scanner support framework arranged about ahigh-speed conveyor belt, and arranged so that each scanning subsystemprojects a highly-defined 3-D omni-directional scanning volume with alarge depth-of-field, above the conveyor structure so as to collectivelyprovide omni-directional scanning within each of the three principalscanning planes of the tunnel-type scanning system.

Another object of the present invention is to provide such a tunnel-typescanning system, in which each holographic laser scanning subsystemprojects a highly-defined 3-D omni-directional scanning volume that hasa large depth-of-field and is substantially free of spatially andtemporally coincident scanning planes, to ensure substantially zerocrosstalk among the numerous laser scanning channels provided withineach holographic laser scanning subsystem employed in the system.

Another object of the present invention is to provide such a tunnel-typescanning system, in which a split-type conveyor is used with a gapdisposed between its first and second conveyor platforms, for mountingof an omni-directional projection-type laser scanning subsystem that isbelow the conveyor platforms and extends substantially the entire widthof the conveyor platform.

Another object of the present invention is to provide such a tunnel-typescanning system, wherein a plurality of holographic laser scanners arearranged about the conveyor system to produce a bi-directional scanningpattern along the principal axes of a three-dimensional laser scanningvolume.

A further object of the present invention is to provide such atunnel-type scanning system, in which each holographic laser scanneremployed in the system projects a three-dimensional laser scanningvolume having multiple focal planes and a highly confined geometryextending about a projection axis extending from the scanning window ofthe holographic scanner and above the conveyor belt of the system.

Another object of the present invention is to provide an improvedtunnel-type scanning system, wherein bar code symbols downwardly facingthe conveyor belt can be automatically scanned as they are transportedthrough the system in a high-speed manner.

Another object of the present invention is to provide an improved methodof scanning bar code symbols within a tunnel-scanning environmentthrough which objects of various types can be conveyed at high transportspeeds.

These and other objects of the present invention will become apparenthereinafter and in the Claims to Invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, thefollowing Detailed Description of the Illustrative Embodiment should beread in conjunction in connection with the accompanying Drawings,wherein:

FIG. 1 is a first perspective view of the tunnel-type laser scanningsystem of the illustrative embodiment of the present invention;

FIG. 1A is a second perspective view of the tunnel-type laser scanningsystem of the present invention, shown in larger scale and with aportion of its conveyor structure removed from the system;

FIG. 1B is an elevated side view of the tunnel-type laser scanningsystem of the illustrative embodiment, removed from the scanner supportframework, in order to clearly show the O-ring conveyor platform forstaggering packages prior to entering the 3-D scanning volume, the lightcurtain associated with the packaging dimensioning subsystem fordetermining the total volume of the package, and whether there aremultiple packages entering the 3-D scanning volume, a scan datamanagement computer system (i.e. station) with a graphical userinterface (GUI) for easily configuring the scanning subsystems withinthe system and monitoring the flow of packages into the scanning tunnel,and an exit sensor for detecting the exit of each scanned package withinthe scanning tunnel;

FIG. 1C is a perspective view of the tunnel-type laser scanning systemof the illustrative embodiment of the present invention, shown ingreater detail, detached from a portion of its roller-based conveyorsubsystem and scan data management subsystem;

FIG. 1D is a perspective view of the split-section conveyor subsystemand its bottom-mounted laser scanning projection subsystem, anduser-interface/workstation, shown detached from the scanner supportframework shown in FIGS. 1, 1A and 1B;

FIG. 2A is a perspective view of the split-conveyor subsystem removedfrom scanner support framework of the system, showing a coordinatereference framework symbolically embedded within the conveyor system andshown with graphical indications describing the directions of yaw, pitchand roll of each triple-scanning disc holographic scanner supported fromthe scanner support framework of the tunnel scanning system shown inFIGS. 1 and 1A;

FIG. 2B is a perspective view of the split-conveyor subsystem removedfrom scanner support framework of the system, showing a coordinatereference framework symbolically embedded within the conveyor system andshown with graphical indications describing the directions of yaw, pitchand roll of each single-scanning disc holographic scanner supported fromthe scanner support framework of the tunnel scanning system shown inFIGS. 1 and 1A;

FIG. 2C is a table setting for data specifying the position andorientation of the sixteen omni-directional holographic laser scannersmounted within the tunnel scanning system of the illustrative embodimentof the invention, wherein the position of each single-disc holographicscanner is specified with respect to the center of the holographicscanning disc contained within each such scanning unit, and the positionof each triple-disc holographic scanner is specified with respect to thecenter of the middle holographic scanning disc contained within eachsuch scanning unit;

FIG. 3A1 is a perspective, partially cut-away view of the single-discholographic laser scanning subsystem (e.g. indicated as L/F Corner #1,L/F Corner #2, L/B Corner #1, L/B Corner #2, R/F Corner #1, R/F Corner#2, R/B Corner #1 and R/B Corner #2 in FIG. 1 and the ScannerPositioning Table shown in FIG. 2C), mounted within the corners of thetunnel-type scanning system of the illustrative embodiment, showing theholographic scanning disc surrounded by one of its six beam foldingmirrors, parabolic light collection mirrors, laser beam productionmodules, photodetectors, and analog and digital signal processing boardsmounted on the optical bench of the subsystem;

FIG. 3A2 is a plan view of the single-disc holographic laser scanningsubsystem employed in the tunnel scanning system of the illustrativeembodiment, showing the holographic scanning disc surrounded by sixlaser scanning stations comprising a beam folding mirror, paraboliclight collection mirror, laser beam production module (employing a VLD),each of which encloses a compact housing adapted for adjustable supportby the scanner support framework employed in the tunnel scanning systemof the illustrative embodiment;

FIG. 3A3 is an cross-sectional view of the single-disc holographic laserscanning subsystem shown in FIG. 3A2, showing its holographic scanningdisc rotatably supported by its scanning motor mounted on the opticalbench of the subsystem;

FIG. 3A4 is a schematic representation of the layout of thevolume-transmission type holographic optical element (HOEs) mountedbetween the glass support plates of the holographic scanning discemployed within the single-disc holographic scanning subsystem employedwithin the tunnel scanning system of the illustrative embodiment;

FIG. 3A5 is a table setting forth the design parameters used toconstruct with the single-disc holographic scanning subsystem employedin the tunnel scanning system of the illustrative embodiment;

FIG. 3A6 is a schematic representation of the laser scanning patternprojected from the single-disc holographic laser scanning subsystememployed in the tunnel-type scanning system of the present invention;

FIG. 3B1 is a plan view of the triple-disc holographic scanningsubsystem (e.g. indicated as Top/Front, Top/Back, Left Side/Front, LeftSide/Back, Right Side/Front and Right Side/Back in FIG. 1 and theScanner Positioning Table shown in FIG. 2C), mounted on the top andsides of the tunnel-type scanning system of the illustrative embodiment,showing three holographic scanning discs mounted on an optical benchwith 13.3 inches spacing between the axis of rotation of eachneighboring holographic scanning disc, and each holographic scanningdisc being surrounded by six beam folding mirrors, six parabolic lightcollection mirrors, six laser beam production modules, sixphotodetectors, and six analog and digital signal processing boardsmounted on the optical bench of the subsystem;

FIG. 3B2 is a schematic representation of the layout of thevolume-transmission type holographic optical elements (HOEs) mountedbetween the glass support plates of each holographic scanning discemployed within the triple-disc holographic scanning subsystem shown inFIG. 3B1;

FIG. 3B3 is a table setting forth the design parameters used toconstruct with the each holographic scanning subsystem employed in thetriple-disc holographic laser scanner shown in FIG. 3B1;

FIG. 3B4 is a schematic representation of the laser scanning patternprojected the single-disc holographic laser scanning subsystem employedin the triple-disc holographic laser scanner shown in FIG. 3B4, whennone beam folding mirrors associated therewith are angularly located orrotated;

FIG. 3B5 is a table setting forth the angular location and rotation ofeach beam folding mirror in the center and end-located holographicscanning subsystems employed in the triple-disc holographic laserscanner shown in FIG. 3B4;

FIG. 3B6 is a schematic representation of the laser scanning patternprojected from the center of the holographic laser scanning subsystememployed in the triple-disc holographic laser scanner shown in FIG. 3B4,wherein each of beam folding mirrors associated therewith are angularlylocated and rotated as shown in the table of FIG. 3B5, to achieve thedesired scanning pattern;

FIG. 3B7 is a schematic representation of the laser scanning patternprojected from end-located holographic laser scanning subsystem employedin the triple-disc holographic laser scanner shown in FIG. 3B4, whereineach of beam folding mirrors associated therewith are angularly locatedand rotated to achieve the desired scanning pattern;

FIG. 3B8 is a schematic representation of the laser scanning patternprojected from the triple-disc holographic laser scanner shown in FIG.3B4;

FIG. 3C1 is a plan view of the triple-disc holographic scanningsubsystem (e.g. indicated as Front and Back in FIG. 1 and the ScannerPositioning Table shown in FIG. 2C), mounted on the top of thetunnel-type scanning system of the illustrative embodiment, showingthree holographic scanning discs mounted on an optical bench with 14.0inches spacing between the axis of rotation of each neighboringholographic scanning disc, and each holographic scanning disc beingsurrounded by six beam folding mirrors, six parabolic light collectionmirrors, six laser beam production modules, six photodetectors, and sixanalog and digital signal processing boards mounted on the optical benchof the subsystem;

FIG. 3C2 is a schematic representation of the laser scanning patternprojected from the triple-disc holographic laser scanner shown in FIG.3C1;

FIG. 3D1 is an exploded diagram of the fixed laser projection scannermounted beneath the conveyor belt surface of the system, and between thefirst and second conveyor belt platforms of the conveyor subsystememployed in the tunnel scanning system of the illustrative embodiment ofthe present invention, showing the optical bench upon which eight fixedprojection-type laser scanning subsystems are mounted and enclosedwithin a scanner housing having a rugged glass scanning window bridgingthe gap provided between the first and second conveyor belt platforms;

FIG. 3D2 is a perspective view of the projection-type laser scanningsubsystem mounted within the bottom-mounted fixed projection scannershown in FIG. 3D1, showing an eight-sided polygon scanning elementrotatably mounted closely adjacent a stationary mirror array comprisedof four planar mirrors, and a light collecting mirror being centrallymounted for focusing light onto a photodetector disposed slightly beyondthe polygon scanning element;

FIG. 3D3 is a plan view of the eight fixed-projection laser scanningsubsystems mounted on the optical bench of the bottom-mounted laserscanner shown in FIG. 3D1;

FIG. 3D4 is a schematic representation of the partial scanning patternproduced by the eight-sided polygon scanning element and two stationarymirrors mounted adjacent the central plane of each fixed-projectionlaser scanning subsystem mounted on the optical bench of thebottom-mounted laser scanner shown in FIG. 3D1;

FIG. 3D5 is a schematic representation of the partial scanning patternproduced by the eight-sided polygon scanning element and two outerstationary mirrors mounted adjacent the two inner-located stationarymirrors in each fixed-projection laser scanning subsystem mounted on theoptical bench of the bottom-mounted laser scanner shown in FIG. 3D1;

FIG. 3D6 is a schematic representation of the complete scanning patternproduced by the eight-sided polygon scanning element and four stationarymirrors mounted about the central plane of each fixed-projection laserscanning subsystem mounted on the optical bench of the bottom-mountedlaser scanner shown in FIG. 3D1;

FIG. 3D7 is a schematic representation of the resultant (collective)omni-directional scanning pattern produced through the conveyor mountedscanning window, by the eight fixed-projection laser scanning subsystemsmounted on the optical bench of the bottom-mounted laser scanner shownin FIG. 3D1;

FIG. 4 is a schematic block diagram illustrating that the holographicand fixed-projection laser scanning subsystems, the package dimensioningsubsystem, and the conveyor belt control subsystem employed within thetunneling scanner of the illustrative embodiment, are interfaced to ascan data management and system configuration computer system through ainput/output port multiplier subsystem;

FIG. 5A is a schematic diagram showing the directions ofomni-directional scanning provided in the X-Y plane of the 3-D scanningvolume of tunnel scanning system hereof, by the Front and Backholographic laser scanning subsystems, and bottom-mounted fixedprojection scanning subsystem employed in the tunnel-type scanningsystem of the present invention;

FIG. 5B is a schematic diagram showing the direction of omni-directionalscanning provided in the Y-Z plane of the 3-D scanning volume of tunnelscanning system hereof, by the bottom-mounted fixed-projection laserscanning subsystem employed in the tunnel-type scanning system of theillustrative embodiment;

FIG. 6 is a schematic diagram showing the direction of omni-directionalscanning provided in the X-Y plane of the 3-D scanning volume of tunnelscanning system hereof, by the Left Side Front, Left Side Back, RightSide Front and Right Side Back holographic laser scanning subsystemsemployed in the tunnel-type scanning system of the illustrativeembodiment;

FIG. 7 is a schematic diagram showing the direction of omni-directionalscanning provided in the Y-Z plane of the 3-D scanning volume of tunnelscanning system hereof, by the Front and Back holographic laser scanningsubsystems employed in the tunnel-type scanning system of theillustrative embodiment;

FIG. 8A is a schematic diagram showing the direction of omni-directionalscanning provided in the Y-Z plane of the 3-D scanning volume of tunnelscanning system hereof, by the holographic laser scanning subsystems(indicated by R/B Corner #1, R/B Corner #2, L/F Corner #1 and R/B Corner#2) employed in the tunnel-type scanning system of the illustrativeembodiment;

FIG. 8B is a schematic diagram showing the direction of omni-directionalscanning provided in the X-Y plane of the 3-D scanning volume of tunnelscanning system hereof, by the holographic laser scanning subsystems(indicated by R/B Corner #1, R/B Corner #2, R/F Corner #1 and RIB Corner#2) employed in the tunnel-type scanning system of the illustrativeembodiment;

FIG. 9A is a schematic diagram showing the direction of omni-directionalscanning provided in the Y-Z plane of the 3-D scanning volume of tunnelscanning system hereof, by the holographic laser scanning subsystems(indicated by L/B Corner #1, L/B Corner #2, L/F Corner #1 and L/B Corner#2) employed in the tunnel-type scanning system of the illustrativeembodiment; and

FIG. 9B is a schematic diagram showing the direction of omni-directionalscanning provided in the X-Y plane of the 3-D scanning volume of tunnelscanning system hereof, by the holographic laser scanning subsystems(indicated by L/B Corner #1, L/B Corner #2, L/F Corner #1 and L/B Corner#2) employed in the tunnel-type scanning system of the illustrativeembodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

Referring to the figures in the accompanying Drawings, the variousillustrative embodiments of the holographic laser scanner of the presentinvention will be described in great detail, wherein like elements willbe indicated using like reference numerals.

In FIG. 1, there is shown a tunnel-type laser scanning system designedto meet the needs of demanding customers, such as the United StatesPostal Service (USPS), who requires “hands-free” bar code (or codesymbol) scanning of at least six-packages, wherein the label containingthe code symbol to be read can be placed in any orientation on any oneof the six or more sides of the box or container structure. As usedhereinafter, the term “hands-free” shall mean scanning of bar codes onboxes or parcels that are traveling past the scanners in only onedirection on some sort of conveyor system.

As shown in FIGS. 1 through 1D, the tunnel scanning system of theillustrative embodiment 1 comprises an arrangement of laser scanningsubsystems (i.e. scanners) which, by virtue of their placement, relativeto a conveyor belt subsystem 2, essentially form a “tunnel” over theconveyor. In the field of package sortation of any sort, whether it bemail, luggage (as in an airport terminal) or other items or boxes, thistype of code symbol scanning system is known as a “tunnel scanningsystem” by those skilled in the art.

The tunnel scanning system of the illustrative embodiment, and shown ingreat detail in the drawings has been designed and constructed to meet aspecific set of customer-defined scanning. parameters. For example, thebar code label can be on any side of a box having six sides. The barcode label can be in any orientation. Furthermore the object bearing thebar code label to be read would move past the scanners on a conveyorbelt travelling at speeds in excess of 400 feet per second. In theillustrative embodiment, the conveyor belt belts 3A and 3B move at 520feet per second. The types of codes to be read include such codes asCode 39, Code 128 and others. The aspect ratio of the bar codes to beread is on the order of 10 mils and up.

The tunnel scanning system of the present invention can be used invarious types of applications, such as for example, where the bar codesare read to determine (a) identification of incoming packages, (b)identification of outgoing packages, and (c) sortation of outgoingpackages. For sortation types of applications, the information derivedfrom the bar code will be used not only to identify the package, butalso to direct the package along a particular path using deflectors,routers and other instruments well known in the package and parcelhandling art.

In the illustrative embodiment, the volume to be scanned within thetunneling system (e.g. its 3-D scanning volume) is approximately: 1meter wide (i.e. the width of the conveyor belt); ten feet long; and 1meter tall (i.e. the height of the tallest possible box going through).The laser scanning pattern produced by, the concerted operation of theholographic laser scanning subsystems identified in the drawings, anddescribed above, fills this entire 3-D scanning volume with over 400,000scan lines per second. The 3-D scanning volume of the tunnel scanningsystem, measured with respect to the surface of the conveyor belt,begins at the surface of the conveyor belt in order to scan flat items(such as envelopes), and extends up approximately 1 meter (“h) above thesurface of the conveyor belt subsystem.

As shown in FIGS. 1 through 1C, sixteen holographic laser scanningsubsystems are mounted on a lightweight scanner support framework 4, atpositions specified in Tunnel Scanner Positioning Data Table shown inFIG. 2C. The terms (e.g. “Top/Front”, Top/Back”, etc.) used in thisTable to identify the individual holographic scanning subsystems of thetunnel scanning system hereof are used throughout the drawings, ratherthan reference numerals. The one fixed-projection scanner subsystem,identify by the label “Bottom”, is mounted between the gap providedbetween the first and second conveyor platforms 3A and 3B comprising theconveyor subsystem of the tunnel scanning system.

Each of the holographic scanners (R/F Corner #1, R/F Corner #2, R/BCorner #1, R/B Corner #2, L/F Corner #1, L/F Corner #2, L/B Corner #1,LIB Corner #2) mounted within the corners of the scanner supportframework are single-disc holographic scanning subsystems, having fivefocal planes, formed using six laser scanning stations, each having aVLD, a beam folding mirror, parabolic light collection mirror, signalprocessing circuit boards and the like, designed and constructed usingthe methods detailed in Applicant's application Ser. Nos. 08/949,915filed Oct. 14, 1997; 08/854,832 filed May 12, 1997; 08/886,806 filedApr. 22, 1997; 08/726,522 filed Oct. 7, 1996; and 08/573,949 filed Dec.18, 1995, each incorporated herein by reference. The design parametersfor the twenty facet holographic scanning disc shown in FIG. 3A4, andthe supporting subsystem used therewith, are set forth in the Table ofFIG. 3A5. Notably, these design parameters set forth in the table ofFIG. 3A5 are defined in detail in the above-referenced U.S. PatentApplications. The scanning pattern projected on the middle (third)focal/scanning plane of each such single-disc holographic scanningsubsystem is shown in FIG. 3A6.

As shown, the two triple-disc holographic scanners (Top Front and TopBack) are mounted above the conveyor belt by way of the scanner supportframework. The four triple-disc holographic scanners (Left Side Front,Left Side Back, Right Side Front and Right Side Back) are mounted on theleft and right sides of the scanner support framework. Each of thesetriple-disc holographic scanning subsystems is shown in greater detailin a FIGS. 3B1 through 3B8. Each of these holographic scanningsubsystems has five focal planes, formed using three sets (groups) ofsix laser scanning stations, arranged about a twenty-facet scanningdisc. Each laser scanning station about-the scanning disc has a VLD, abeam folding mirror, parabolic light collection mirror, signalprocessing circuit boards and the like. Each holographic laser scanningsubsystem within these triple-disc scanners designed and constructedusing the methods detailed in Applicant's application Ser. Nos.08/949,915 filed Oct. 14, 1997; 08/854,832 filed May 12, 1997;08/886,806 filed Apr. 22, 1997; 08/726,522 filed Oct. 7, 1996; and08/573,949 filed Dec. 18, 1995, each incorporated herein by reference.The design parameters for each twenty facet holographic scanning discshown in FIG. 3B2, and the supporting subsystem used therewith, are setforth in the Table of FIG. 3B3. Notably, the design parameters set forthin the table of FIG. 3B3 are defined in detail in the above-referencedUS Patent Applications. The scanning pattern projected on the middle(third) focal/scanning plane of each such triple-disc holographicscanning subsystem is shown in FIG. 3B8.

As shown, the two triple-disc holographic scanners (Front and Back) aremounted above the conveyor belt by way of the scanner support framework.Each of these triple-disc holographic scanning subsystems is shown ingreater detail in FIGS. 3C1 and 3C2. Each of these holographic scanningsubsystems has five focal planes, formed using three sets (groups) ofsix laser scanning stations, arranged about a twenty-facet scanningdisc. Each laser scanning station about the scanning disc arranged has aVLD, a beam folding mirror, parabolic light collection mirror, signalprocessing circuit boards and the like. Each holographic laser scanningsubsystem within these triple-disc scanners is designed and constructedusing the methods detailed in Applicant's application Ser. Nos.08/949,915 filed Oct. 14, 1997; 08/854,832 filed May 12, 1997;08/886,806 filed Apr. 22, 1997; 08/726,522 filed Oct. 7, 1996; and08/573,949 filed Dec. 18, 1995, each incorporated herein by reference.The design parameters for each twenty facet holographic scanning discshown in the table of FIG. 3A4, and the supporting subsystem usedtherewith, are set forth in the Table of FIG. 3A5. Notably, the designparameters set forth in the table of FIG. 3A5 are defined in detail inthe above-referenced U.S. Patent Applications. The scanning patternprojected on the middle (third) focal/scanning plane of each such tripledisc holographic scanning subsystem is shown in FIG. 3C2.

The bottom-mounted fixed projection scanner (Bottom) employed in thetunnel scanning system hereof is shown in greater detail in FIGS. 3D1through 3D7. As shown in FIG. 3D1, the bottom-mounted scanner compriseseight fixed-projection laser scanning subsystems 6, shown in FIG. 3D2,that are mounted along optical bench 7 shown in FIG. 3D1. Each fixedprojection scanning subsystem 6 comprises: four stationary mirrors 8arranged about a central reference plane passing along the longitudinalextent of the optical bench 8 of the subsystem; and eight-sided motordriven polygon scanning element 10 mounted closely to the nested arrayof mirrors 8; a light collecting mirror 9 mounted above the nested arrayalong the central reference plane; a laser diode 11 for producing alaser beam which is passed through collecting mirror 9 and strikes thepolygon 10; and a photodetector 12, mounted above the polygon, fordetecting reflected laser light in a manner well known in the art toproduce scan data signals for signal processing.

In FIGS. 3D4 and 3D5, the partial scan pattern produced by individualstationary mirrors in each subsystem 6 are shown. The complete patterngenerated by each subsystem 6 is shown in FIG. 3D6. The compositeomnidirectional scanning pattern generated by the eight subsystems 6working together in the bottom scanner is shown in FIG. 3D7.

In FIG, 4, the seventeen individual scanning subsystems within thetunnel scanning system hereof (indicated by reference number 101 through117) are interfaced with a scan data management and system configurationcomputer system 120 by way of an I/O port multiplier 121 well known inthe art. The computer system has a GUI 122 supported by a displayterminal, mouse, keyboard and the like. This GUI enables programming ofthe system and the like.

In FIGS. 5A through 9B, the various omnidirectional scanning directionsprovided for within the 3-D scanning volume of the tunnel scanner of thepresent invention are schematically illustrated. These illustrationsindicate how each of the laser scanning subsystems within the tunnelscanning system contribute to produce the truly omnidirectional scanningperformance attained by the tunnel scanner hereof.

The tunnel scanning system of the present invention can read differentbar code symbologies (Interleaved two of five, Code 128 and Code threeof nine) and formats so as to sort and identify packages at variouspackage rates required by USPS or other end-user. The system of theillustrative embodiment can read the ZIP Code (six digits), PackageIdentification Code (PIC) (sixteen characters) and the Tray bar code(ten digits) symbols.

The tunnel scanning system hereof can be configured so that all of theproducts passing through the “tunnel” shall be scanned and read for thevalid USPS bar coded symbols regardless of the position of the BCS onthe surface of the product. This also includes the bottom surface of theproduct.

The tunnel scanning system hereof can be provided with equipment such astachometers, dimensioning units, support structures, special power units(if required), air compressors and any other support equipment.

Preferably the tunnel scanning system of the present invention isconstructed using standard interfaces such that scanners, decoders,concentrator, etc. are interchangeable.

The tunnel scanning system hereof can read bar coded symbols through theentire population of tray and tub label holders in use by the USPS. Inaddition, the tunnel scanning system can read BCS on the packageproducts when the BCS label is placed under diaphanous materials.

There will be more than one symbol (BCS) on many of the packages foundin the tunnel system hereof. Some of these symbols will not be validUSPS symbols. If there are multiple symbols on a package, the scannerlogic will automatically identify and process only the USPS validsymbols.

The tunnel scanning system of the present invention can process alltypes of products found in BMC's (e.g. trays and tubs having extremelylarge variance in surface types and colors, e.g. plastics, Tyvekmaterial, canvass, cardboard, polywrap, Styrofoam, rubber, darkpackages). Some examples of these product types include:Softpack-Pillows, bags. Flats; Trays and tubs with and without bands.Cartons; Rugs, duffel bags (without strings or metal clips);mixed-tires, wooden containers Sacks; and Tires.

What is claimed is:
 1. An automated holographic-based tunnel-type laserscanning system capable of scanning bar code symbols applied to thesurfaces of packages facing along any direction or orientation within athree-dimensional scanning volume disposed above a conveyor beltstructure, said automated holographic-based tunnel-type laser scanningsystem comprising: a conveyor belt structure for transporting packagesalong a predetermined direction of travel, said conveyor belt structurehaving a width dimension and first and second conveyor platformsarranged closely together in a predetermined direction, with a gapregion disposed between said first and second conveyor platforms andextending across said width dimension of said conveyor belt structure,and each said package having a plurality of surfaces and a bar codesymbol applied to at least one said surface and each said package beingarrangeable on said conveyor belt structure in any arbitrary orientationfor transport along said predetermined direction of travel; a scannersupport framework arranged above a first position of said conveyor beltstructure for supporting a plurality of holographic laser scanningsubsystems above said conveyor belt structure so as to form atunnel-type structure through which said conveyor belt structure extendsand along which said packages are transported in an automated manner; abottom-located scanning subsystem disposed between said gap region insaid conveyor belt structure, for producing an omni-directional scanningpattern along substantially the entire width dimension of said conveyorbelt structure; and a plurality of holographic laser scanning subsystemsmounted from said scanner support framework and arranged so that eachsaid holographic laser scanning subsystem projects an omni-directionallaser scanning pattern confined substantially within a three-dimensionallaser scanning volume disposed above said conveyor belt structure andhaving a large depth-of-field; and wherein the omni-directional scanningpattern produced from said bottom-located scanning subsystem and theplurality of omni-directional laser scanning patterns produced from saidplurality of holographic laser scanning subsystems cooperate andcollectively produce a composite three-dimensional scanning patterncontained within an entire three-dimensional scanning volume disposedwithin said tunnel-type structure and above said conveyor beltstructure, enabling the automated scanning of bar code symbols appliedto the surfaces of said packages facing any direction or orientationwithin said entire three-dimensional scanning volume, and production ofsymbol character data representative of each said scanned bar codesymbol.
 2. The automated holographic-based tunnel-type laser scanningsystem of claim 1, wherein the omnidirectional laser scanning patternproduced by each said holographic laser scanning subsystem has multiplefocal planes and a highly confined geometry extending about a projectionaxis extending from a scanning window provided within said holographiclaser scanning subsystem and above said conveyor belt structure.
 3. Theautomated holographic-based tunnel-type laser scanning system of claim 1wherein said entire three-dimensional scanning volume has a widthwisedimension of at least about 1 meter extending along the width dimensionof said conveyor belt structure, a lengthwise dimension of at least 1meter extending along said predetermined direction of travel, and aheightwise dimension of at least 1 meter extending about said conveyorbelt structure.
 4. The automated holographic-based tunnel-type laserscanning system of claim 1, wherein said composite three-dimensionallaser scanning pattern fills said entire three-dimensional scanningvolume with at least 100,000 scan lines per second.
 5. The automatedholographic-based tunnel-type laser scanning system of claim 1, whereinsaid plurality of holographic laser scanning subsystems are mountedwithin the corners of said scanner support framework, on the top andsides of said scanner support framework, and on the front and back ofsaid scanner support framework.
 6. The automated holographic-basedtunnel-type laser scanning system of claim 1, wherein saidbottom-located scanning subsystem comprises a projection-type laserscanning subsystem.
 7. The automated holographic-based tunnel-type laserscanning system of claim 1, which further comprises a packagedimensioning subsystem, installed along a second portion of saidconveyor belt structure, for measuring the dimensions of each packagebeing transported through said tunnel-like structure.
 8. The automatedholographic-based tunnel-type laser scanning system of claim 1, whichfurther comprises a computer system interfaced with said plurality ofholographic laser scanning subsystems and said bottom-located scanningsubsystem through an input/output port multiplier, said computer systemsupporting functions including scan data management and systemconfiguration.